Electronic design often requires the use of various interface circuitries such as liquid crystal displays (LCDs) and capacitive sensor arrays that enable the user to interact with or receive information from an electronic circuit. Typically, LCD displays are driven by dedicated LCD controllers which enable a circuit to control an LCD display to display desired information on the segments of the LCD display. Similarly, dedicated sensing circuitry may be used to detect the activation of capacitive switches within a capacitive sensor array enabling a user to input particular information to a circuit.
In control devices wherein the output pins may be configured to perform either of the functionalities of driving an LCD display or enabling sensing of signals from a capacitive sensor array, there is the possibility of both digital and/or analog signals being provided to the input/output pins. The voltage operating ranges of the input/output pins may vary depending upon whether analog or digital signals are being utilized and based upon the type of analog or digital signal that is being applied to the pin. Should these voltages applied to the input pins exceed bias voltages that are applied to various circuitries and transistors within the LCD controller various circuit malfunctions or glitches may occur. Thus, there is a need to ensure that a situation does not arise wherein voltages applied to I/O pads of LCD controller circuitries do not exceed the bias voltages applied to various circuitries and transistors for operating the I/O pads of the LCD controller.